The invention relates to an apparatus and a method for gathering documents. An example of such an apparatus is disclosed in European patent 0 566 922. In this apparatus, the documents to be gathered, in practice generally main documents and enclosures to be added thereto, are placed in separate feeding stations and transported along a supply track towards a gathering station. Unlike enclosures, sheets or other postal items constituting main documents usually contain information intended for a specific addressee. In particular if enclosures are to be added to main documents selectively in accordance with marks read from the main document, the enclosures of each set are preferably fed after the personalized or address carrying sheets of the main document of the respective set. The enclosures are fed in response to the feeding of the last main document of a set. The feeding of the last main document of a set may, for example, be detected by a sensor for scanning markings on a sheet and generating a signal in accordance with the scanned markings, which signal providing an indication whether or not the last sheet of a main document of a set has been fed.
For obtaining a small, compact and low cost system, it is advantageous that the gathering of a set occurs downstream of the feeding stations and that the sensor along the supply track can scan markings from all documents (main documents and enclosures).
Sometimes markings indicating that a document is a last main document of a set are not provided. Instead only a marking is provided on each first main document of each set. This would present a problem because, when markings on a document are detected indicating that it is the first main document of a next set, the previous main document was the last main document of the set being gathered and the first document of the next set would be added to the wrong set or block the supply track for enclosures to be added to the completed set of main documents.